成人快手

In the beginning.... the solar system was an extremely chaotic place, with gas, dust and rock flying in all directions around the newly-formed Sun. The rock gradually coalesced into planets, but many of them had very erratic orbits, crossing the paths of other objects, sometimes with catastrophic results. And in one of the most dramatic events in the early history of our solar system a Mars-sized planet called Theia hit the newly-formed Earth. Dr. Sara Russell is a planetary scientist from the Natural History Museum in London. She explains how, four-and-a-half billion years ago, two worlds collided and created the Moon.